There have been many diverse separation methods beyond those normally found in standard texts. Diverse evaporators and dryers have been employed to effect separation of liquids from solids with which they are admixed or otherwise associated.
Although "distillation" is commonly used in the sense of vaporizing a single constituent from a solution, e.g., in distilling water, the term is properly applied only where vaporization of a liquid mixture yields a vapor phase containing more than one constituent, and it is desired to recover one of more of these constituents in a nearly pure state. Thus, the process of separating liquids from solids by vaporizing the liquid is properly referred to as evaporation or drying.
Stone (U.S. Pat. No. 1,996,938) provides a "Method of Distillation" and associated apparatus. His operation is designed to be effected at near room temperature and at reduced pressure, e.g. 17.363 mm. of mercury. Purification of water is thus effected by vaporization and condensation.
Andersen (U.S. Pat. No. 2,619,453) relates to a method for liquid evaporation and solid concentration. The liquid to be evaporated is forceably circulated through one part of a heat exchanger, in another part of which the vapors are condensed after having been subjected to a compression.
Nickerson (U.S. Pat. No. 3,147,201), like Andersen, refers to "Vapor Compression Distillation ". He provides apparatus which uses natural gravitational currents to remove concentrated solution from an evaporation chamber, which is very compact in relation to its capacity. A single vacuum pump or compressor is used to raise the solution to the evaporation chamber, to lower the saturation temperature of the solution and to compress vapors evolved from the solution to provide heat necessary for continuous evaporation.
Harper (U.S. Pat. No. 3,275,532) relates to evaporating and condensing a liquid, e.g., for condensing fresh water from sea water. Water vapor is evaporated from sea water into a confined space which is at a certain pressure. An equilibrium is established between the sea water and the vapor in a confined space. Water is condensed from the vapor phase by increasing pressure on the confined space. Condensed water is then removed.
Brown (U.S. Pat. No. 3,597,329) effects evaporation by distributing feed liquid onto a plurality of opposite-facing substantially-parallel and substantially-vertical surfaces. Between neighboring oppositely-facing surfaces he establishes a vapor zone for evaporation and vapor removal.
Wilson (U.S. Pat. No. 3,637,465) is also primarily concerned with making potable water from sea water or water otherwise contaminated with impurities. He provides a distillation system in which heat flows from fluid being cooled to fluid being heated in a manner which is essentially recirculating counterflow exchange.